262 COSMOS. 



mica-slate, and in the schistose group in the western part 

 of the island of Elba, near the promontory of Calamita, and 

 the Fichtelgebirge in Baireuth, between Lomitz and Mark- 

 leiten.* 4 



Jasper, which,f as I have already remarked, is a production 

 formed by the volcanic action of augitic porphyry, could only 

 be obtained in small quantities by the ancients, whilst another 

 material, very generally and efficiently used by them in the 

 arts, was granular or saccharoidal marble, which is likewise to 

 be regarded solely as a sedimentary stratum altered by terrestrial 

 heat and by proximity with erupted rocks. This opinion is 

 corroborated by the accurate observations on the phenomena 

 of contact, by the remarkable experiments on fusion, made by 

 Sir James Hall more than half a century ago, and by the 

 attentive study of granitic veins, which has contributed so 



the Gries-glaciers), and the belemnites found by M. Charpentier in the 

 so-called primitive limestone on the western descent of the Col de la 

 Seigne, between the Enclove de Montjovet and the chalet of La Lan- 

 chette, and which he showed to me at Bex in the autumn of 1822 

 (Annales de Chimie, t. xxiii. p. 262). 



* Hoffmann, in Poggend. A nnalen, bd. xvi. s. 552, " Strata of tran- 

 sition argillaceous schist in the Fichtelgebirge, which can be traced for 

 a length of 16 miles, are transformed into gneiss only at the two extre- 

 mities, where they come in contact Avith granite. We can there follow 

 the gradual formation of the gneiss, and the development of the mica 

 and of the feldspathic amygdaloids, in the interior of the argillaceous 

 schist, which indeed contains in itself almost all the elements of these 

 substances." 



f Amongst the works of art which have come down to us from the an- 

 cient Greeks and Romans, we observe that none of any size as columns 

 or large vases are formed from jasper ; and even at the present day 

 this substance, in large masses, is only obtained from the Ural mountains. 

 The material worked as jasper from the Rhubarb mountain (Reveniaga 

 Sopka), in Altai, is a beautiful ribboned porphyry. The word jasper is 

 derived from the Semitic languages, and from the confused descriptions of 

 Theophrastus (De Lapidibus, 23 and 27) and Pliny (xxxvii. 8 and 9), 

 who rank jasper amongst the " opaque gems," the name appears to have 

 been given to fragments of jaspachat, and to a substance which the 

 ancients termed jasponyx, which we now know as opal-jasper. Pliny 

 considers a piece of jasper eleven inches in length so rare, as to require 

 his mentioning that he had actually seen such a specimen : " Magnitu- 

 dinem jaspidis uridecim unckrurn vidimus, formatamque inde effigiem 

 Keronis thoracatam." According to Theophrastus, the stone which he 

 calls emerald, and from which large obelisks were cut, must have been 

 :an imperfect jasper. 



